The university chemistry professor and his hospital administrator wife sat in my office, staring in astonishment. My medical evaluation was divergent from 2 other consultants who had given conflicting opinions. I was supposed to “break the tie,” but instead, I had outlined a third treatment strategy. These two highly analytical people wanted to know: how could three cardiologists come to such diverse answers based on the same medical information? Wasn’t there something like a decision tree, in which there was a logical sequence to follow based on the results of tests and the severity of disease?

How doctors determine which treatment choice to employ is almost never formally discussed. Cardiology societies have created detailed guideline documents and appropriate use criteria, counseling that clinical decisions be supported by the evidence base, which is gathered and developed from clinical trial results and registry data. However, as this case of stable angina illustrates, there is wide variability in how physicians evaluate symptom severity and interpret test results. There are frequently differences of opinion as to whether a patient fits into a particular trial or may have been excluded on the basis of the study’s inclusion criteria. Consequently, the application of existing knowledge to patient management is often ambiguous.

Increasingly, this is not merely an “ivory tower” dilemma; how clinical decisions are made transcends our view of who is a good doctor and whether a patient is being managed appropriately and cost effectively. As physician report cards and reimbursement based on outcomes enter everyday practice, misunderstandings between those who make the decisions and those who appraise them may create a “Tower of Babel” predicament in which lack of communication leads to incorrect physician quality assessments. We have all observed cases in which an accomplished physician made a decision with which we disagreed; sometimes, discussing the circumstances with that doctor illuminates unrecognized details or considerations. As cardiology proceeds with external evaluations of quality, it is important that doctors comprehend how we think so we can explain the process to those who do not routinely make medical decisions.

How do doctors think?

Although cardiologists take great pride in our scientific and quantitative backgrounds, and genuinely believe that the science of medicine is central to making logical decisions, in fact, medical decision making is more art than science. Most of us have a poor comprehension of the interplay between these 2 aspects of our skill set.

The classic manner in which physicians are taught to make a provisional diagnosis is symptom based: we evaluate each patient complaint and arrive at a list of possible explanations, the “differential diagnosis.” Rather than following a formal logic system, physicians think empirically, and solve problems heuristically; that is, the diagnosis is arrived at through an experimental mental process of trial and error. Doctors initially conjecture which possibilities are most common or most critical to exclude first, then discard those and try out others when evidence arises that makes them less likely (1). Sometimes, intuition is relied upon, and first impressions are often correct. When to consider an unlikely, but grave, diagnosis as opposed to a common and more likely but less serious one may be triggered by a patient’s choice of phrase or a laboratory test result. Doctors also think systemically, that is, we evaluate symptoms in the context of diseases or risk factors the patient is known to have.

There is no established organized structure to diagnostic problem solving. Although algorithms have been developed for several situations, the foundation of these methods remains rooted in the symptom-based methods of the past, which are inherently less useful when symptoms are vague or test results have multiple possible explanations.

Therapeutic decision making

Therapeutic decisions are based on randomized trial results filtered through personal observations of how previous patients fared. Not infrequently, doctors reach similar conclusions but arrive there by different reasoning. The reason is that in coronary heart disease, there are just 3 strategic choices—bypass surgery, stenting, and medical therapy—and all are effective to some extent in everybody. Preference among them arises because there are intrinsic drawbacks to each and because the likelihood of risk varies depending on individual circumstances. The challenge is to determine whether 1 modality holds a special advantage or disadvantage for the individual patient. No patient wants to endure the pain and recuperative process of surgery if there is no incremental benefit; conversely, no patient will accept the cost and hassle of multiple medications and their adverse effects if there is a better alternative. Further, it is reasonable to avoid expensive procedures unless there is some measurable improvement over other options. There is no objective way to compare different rates of successes and failures on a subjective, and individual, scale as to which to anticipate and which to fear among the outcomes.

One major gap in our understanding is appreciating how evidence from clinical trials are incorporated—or not—into everyday practice. For example, evaluations of the impact of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial and OAT (Occluded Artery Trial) have shown that these trials and ensuing guidelines have resulted in little or no change in practice. This result has been misunderstood as interventional cardiologists’ lacking interest in scientific evidence, or worse, a preoccupation with income. The reality is that these studies’ designs resulted in a large number of exceptions. Additionally, the development of drug-eluting stents while these studies were in progress has raised questions if the results are applicable in contemporary practice.

Assessing quality: getting with the guidelines

To know what quality practice entails requires the collection of standardized data that accurately reflect patient risk, treatment, and outcome. Monitoring how guideline-mandated therapies are used after implementing quality improvement efforts and then measuring how these changes impact outcomes is the process used to improve practice. Yet certain drug treatments and interventions (2,3) are not always used as mandated by guidelines. Interventional cardiologists should be able to justify when clinical decisions are made that are not fully aligned with guidelines; however, their uncritical application without regard for their limitations may also lead to deficient outcomes. A basic question that must be asked is why interventionists do not follow some guidelines if they are indeed the cornerstone of quality.

One highly cited example is the Appropriate Use Criteria for Coronary Revascularization (3), an algorithm developed from a matrix of clinical variables describing when bypass surgery, coronary stenting, or medical therapy is best employed, keyed to the medical evidence. This tool serves as a quality metric in combination with the National Cardiovascular Data Registry (4). Although a very useful starting point, especially to evaluate populations of patients, this tool is imperfect when applied to individuals (5). The appropriate use criteria assume the absence of extenuating circumstances and that the patient has no strong feelings as to what treatment strategy should be employed (6). Because every patient is unique, and nearly all have preconceived notions concerning treatment choices, these assumptions oversimplify decision making. Although usually applicable in clinical practice, there must be some leeway for specific cases with unusual attributes or concerns.

Another problem is that there are differing opinions as to what constitutes a clinically meaningful effect. Obviously, mortality is 1 crucial outcome measure to determine efficacy, but it is not the only relevant endpoint; stroke and myocardial infarction are also important endpoints. How should a cardiologist interpret SYNTAX, which showed benefit for some endpoints for surgery and benefit for stenting with other endpoints? The need for additional procedures, repeat hospitalization, sustained angina relief, less medication use, and quality of life are also important. These “soft” endpoints are not the primary outcomes of most clinical trials, but to patients, these may be more vital in making decisions than clinical outcomes. When confronted with an elderly patient who is most concerned with improving quality of life, cardiologists have almost no hard data for reference (7).

Another major influence is that of risk aversion. Risk aversion is a reaction to uncertainty in decision making. Although most humans seek the choice that minimizes uncertainty and risk, rational decisions take into account the potential benefits, and the opportunity cost of losing the potential advantages, of riskier choices. Most physicians and patients tend to choose the course they consider to have the lowest risk, rather than the one that optimizes overall benefit. Additionally, it is my observation that it is a perception of higher short-term risk, even if the long-term risk is similar or actually lower, that leads to risk-averse medical decision making. In part, this behavior is strongly influenced by the medical malpractice system, in which a bad short-term result is a basis for legal action. Further, it is emotionally powerful for the physician to select a treatment strategy only to witness a complication consequent to that choice. The advent of national registries and states with public reporting accentuate this apprehension by measuring only the short-term downside. The same quality assurance methods that physicians implement for self-assessment rewards risk aversion by equating complications with lack of skill, which is often inaccurate.

Implications for quality assurance

All of these factors played a role in my assessment of the university professor. He chose the medication route I advised. He lost weight, found time to exercise several times a week despite continuing to teach and do research, and changed his diet. He remained asymptomatic for over 10 years, never requiring any further procedures.

But that is not the end of the story. Although this patient vignette has a happy ending, was it the only solution that should be made available? Just because 1 patient does well does not indicate that the decision making was flawless. Do the other 2 cardiologists deserve criticism for an incorrect therapeutic plan? If angina had worsened in year 2 or 3, necessitating an emergent procedure, would that have rendered my advice incorrect? The choice of which therapeutic alternative is best should ideally be the patient’s decision; our role as physicians is to teach and advise.

In a brave new world of electronic medical records, and administrative and professional databases, it is critical to facilitate clear communication among the various stakeholders and assure the accurate interchange of data and information. It is of no benefit to anyone if the physicians managing the patient and the administrative personnel assessing a system-wide approach are not communicating. Not understanding how interventional cardiologists think raises problems that will be confronted when physician reimbursement is increasingly made on the basis of results, not fee-for-service. If the healthcare system fails to develop a mechanism for decision review that considers how doctors make decisions, it will predictably and inevitably lead to disillusionment. Which “results” are important to society? How much differential in cost is worth what degree of improved outcomes and what level of patient and physician comfort with the decisions? Will the wealthy be able to purchase a different treatment modality that the poor cannot afford?

The serious implication of our confusion as to how doctors make therapeutic decisions is that there are some with other agendas who will seek to make them for us. If we are unable to explain our decision-making process to patients and third party payers, they may find attractive a formulaic answer that seems to remove the elements of ambiguity and doubt. When physician report cards, third-party assessments of hospital and physician quality, ties between outcomes and reimbursement, and the public reporting of outcomes become realities, who will define what is quality practice? And on what basis (8)? It is obligatory that cardiologists lead the process of developing the most rigorous and accurate means to measure quality, develop tools for quality assurance, and support improvement initiatives through standardized assessment of risk, risk adjustment, clinical process, and outcome.

(2012) ACCF/SCAI/STS/AATS/AHA/ASNC 2012 appropriateness criteria for coronary revascularization focused update: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, Society for Cardiovascular Angiography and Interventions, Society of Thoracic Surgeons, American Association for Thoracic Surgery, American Heart Association, American Society of Nuclear Cardiology, and the Society of Cardiovascular Computed Tomography. J Am Coll Cardiol59:857–881.

(2011) Quality assessment and improvement in interventional cardiology. A position statement of the Society of Cardiovascular Angiography and Interventions. Part II. Public reporting and risk-adjustment. Catheter Cardiovasc Interv78:493–502.